Update delta/diff compression impl

server/channelserver/compression/deltacomp/deltacomp.go

@@ -0,0 +1,86 @@
+package deltacomp
+
+import (
+	"errors"
+
+	"github.com/Andoryuuta/byteframe"
+)
+
+func checkReadUint8(bf *byteframe.ByteFrame) (uint8, error) {
+	if len(bf.DataFromCurrent()) >= 1 {
+		return bf.ReadUint8(), nil
+	}
+	return 0, errors.New("Not enough data")
+}
+
+func checkReadUint16(bf *byteframe.ByteFrame) (uint16, error) {
+	if len(bf.DataFromCurrent()) >= 2 {
+		return bf.ReadUint16(), nil
+	}
+	return 0, errors.New("Not enough data")
+}
+
+func readCount(bf *byteframe.ByteFrame) (int, error) {
+	var count int
+
+	count8, err := checkReadUint8(bf)
+	if err != nil {
+		return 0, err
+	}
+	count = int(count8)
+
+	if count == 0 {
+		count16, err := checkReadUint16(bf)
+		if err != nil {
+			return 0, err
+		}
+		count = int(count16)
+	}
+
+	return int(count), nil
+}
+
+// ApplyDataDiff applies a delta data diff patch onto given base data.
+func ApplyDataDiff(diff []byte, baseData []byte) []byte {
+	// Make a copy of the base data to return,
+	// (probably just make this modify the given slice in the future).
+	baseCopy := make([]byte, len(baseData))
+	copy(baseCopy, baseData)
+
+	patch := byteframe.NewByteFrameFromBytes(diff)
+
+	// The very first matchCount is +1 more than it should be, so we start at -1.
+	dataOffset := -1
+	for {
+		// Read the amount of matching bytes.
+		matchCount, err := readCount(patch)
+		if err != nil {
+			// No more data
+			break
+		}
+
+		dataOffset += matchCount
+
+		// Read the amount of differing bytes.
+		differentCount, err := readCount(patch)
+		if err != nil {
+			// No more data
+			break
+		}
+		differentCount -= 1
+
+		// Apply the patch bytes.
+		for i := 0; i < differentCount; i++ {
+			b, err := checkReadUint8(patch)
+			if err != nil {
+				panic("Invalid or misunderstood patch format!")
+			}
+			baseCopy[dataOffset+i] = b
+		}
+
+		dataOffset += differentCount - 1
+
+	}
+
+	return baseCopy
+}

server/channelserver/compression/deltacomp/deltacomp_test.go

@@ -0,0 +1,113 @@
+package deltacomp
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"io/ioutil"
+	"testing"
+
+	"github.com/Andoryuuta/Erupe/server/channelserver/compression/nullcomp"
+)
+
+var tests = []struct {
+	before  string
+	patches []string
+	after   string
+}{
+	{
+		"hunternavi_0_before.bin",
+		[]string{
+			"hunternavi_0_patch_0.bin",
+			"hunternavi_0_patch_1.bin",
+		},
+		"hunternavi_0_after.bin",
+	},
+	{
+		// From "Character Progression 1 Creation-NPCs-Tours"
+		"hunternavi_1_before.bin",
+		[]string{
+			"hunternavi_1_patch_0.bin",
+			"hunternavi_1_patch_1.bin",
+			"hunternavi_1_patch_2.bin",
+			"hunternavi_1_patch_3.bin",
+			"hunternavi_1_patch_4.bin",
+			"hunternavi_1_patch_5.bin",
+			"hunternavi_1_patch_6.bin",
+			"hunternavi_1_patch_7.bin",
+			"hunternavi_1_patch_8.bin",
+			"hunternavi_1_patch_9.bin",
+			"hunternavi_1_patch_10.bin",
+			"hunternavi_1_patch_11.bin",
+			"hunternavi_1_patch_12.bin",
+			"hunternavi_1_patch_13.bin",
+			"hunternavi_1_patch_14.bin",
+			"hunternavi_1_patch_15.bin",
+			"hunternavi_1_patch_16.bin",
+			"hunternavi_1_patch_17.bin",
+			"hunternavi_1_patch_18.bin",
+			"hunternavi_1_patch_19.bin",
+			"hunternavi_1_patch_20.bin",
+			"hunternavi_1_patch_21.bin",
+			"hunternavi_1_patch_22.bin",
+			"hunternavi_1_patch_23.bin",
+			"hunternavi_1_patch_24.bin",
+		},
+		"hunternavi_1_after.bin",
+	},
+	{
+		// From "Progress Gogo GRP Grind 9 and Armor Upgrades and Partner Equip and Lost Cat and Manager talk and Pugi Order"
+		// Not really sure this one counts as a valid test as the input and output are exactly the same. The patches cancel each other out.
+		"platedata_0_before.bin",
+		[]string{
+			"platedata_0_patch_0.bin",
+			"platedata_0_patch_1.bin",
+		},
+		"platedata_0_after.bin",
+	},
+}
+
+func readTestDataFile(filename string) []byte {
+	data, err := ioutil.ReadFile(fmt.Sprintf("./test_data/%s", filename))
+	if err != nil {
+		panic(err)
+	}
+	return data
+}
+
+func TestDeltaPatch(t *testing.T) {
+	for k, tt := range tests {
+		testname := fmt.Sprintf("delta_patch_test_%d", k)
+		t.Run(testname, func(t *testing.T) {
+			// Load the test binary data.
+			beforeData, err := nullcomp.Decompress(readTestDataFile(tt.before))
+			if err != nil {
+				t.Error(err)
+			}
+
+			var patches [][]byte
+			for _, patchName := range tt.patches {
+				patchData := readTestDataFile(patchName)
+				patches = append(patches, patchData)
+			}
+
+			afterData, err := nullcomp.Decompress(readTestDataFile(tt.after))
+			if err != nil {
+				t.Error(err)
+			}
+
+			// Now actually test calling ApplyDataDiff.
+			data := beforeData
+
+			// Apply the patches in order.
+			for i, patch := range patches {
+				fmt.Println("patch index: ", i)
+				data = ApplyDataDiff(patch, data)
+			}
+
+			if !bytes.Equal(data, afterData) {
+				t.Errorf("got out\n\t%s\nwant\n\t%s", hex.Dump(data), hex.Dump(afterData))
+			}
+		})
+	}
+}